Bryce "Zoom to Selection" Function in Blender?
If the idea is to move your camera towards the rectangle selection,
you can lock the camera to view (in "N" panel) and use Shift+B
if you want to really "Zoom" perfectly in your rectangle, you can use this addon I made : https://caetano-veyssieres.com/blender/, using the "Crop" button and multiplying the resolution to your needs. You can't re-iterate the process at the moment but I hope to make it possible.